use "C:\Users\jkbrueck\Documents\STATA\Fuel 3\aviation3.dta", clear
keep if carrier == "AA" | carrier =="UA" | carrier == "DL" | carrier == "B6" ///
| carrier == "WN" | carrier == "NW" | carrier == "CO" | carrier == "US" | ///
carrier == "AS"
  
collapse (mean) gallons_seat_mile, by(year)

graph twoway line gallons_pax_mile gallons_seat_mile year



